Tire parameter sensing systems for vehicles typically include a plurality of tire-based units and a single vehicle-based unit. Each tire-based unit is associated with a tire of the vehicle and is operative to sense at least one parameter of the tire, such as temperature, pressure, etc., and to transmit a parameter signal indicative of the sensed parameter(s). The vehicle-based unit receives parameter signals from the tire-based units and provides an indication to the vehicle operator of the sensed tire parameters.
With the use of run flat tire technology on modern vehicles, it may be difficult for a vehicle operator, when notified of an improper tire parameter, to determine the location of the tire having the improper parameter. For example, when a low tire pressure condition is sensed in one tire of a vehicle having four low profile, run flat tires, the vehicle operator may have difficulty in determining which tire has the low pressure condition by simply looking at the tires. As a result, it is becoming increasingly desirable for tire parameter sensing systems to indicate the corner location on the vehicle at which the improper tire parameter has been sensed.
Many current tire parameter sensing systems assign unique identification numbers to each tire-based unit. The vehicle-based unit is programmed with the identification numbers of the tire-based units and the associated corner location on the vehicle of the each tire-based unit. For example, an identification number of a tire-based unit that is located in a tire located in a front, left corner location on the vehicle is programmed into the vehicle-based unit and is associated with the front, left corner location. Thus, when the vehicle-based unit receives a parameter signal that includes the identification number, the vehicle-based unit associates the tire parameters received in the parameter signal with the front, left corner location on the vehicle.
It is common during routine maintenance of a vehicle for the tires of the vehicle to be rotated. Rotation of the tires places the tire-based units in different locations on the vehicle. As a result, the vehicle-based unit must be reprogrammed to associate the identification numbers of the tire-based units with the different corner locations on the vehicle. Reprogramming the vehicle-based unit can be labor intensive. Thus, a tire parameter sensing system in which the vehicle-based unit is automatically reprogrammed with identification numbers of the tire-based units and the associated vehicle corner locations is desirable.
Copending U.S. patent application Ser. No. 09/687,709, which is assigned to the assignee of the present invention, discloses a tire condition communication system in which low frequency initiators are controllably coupled to the vehicle-based unit. Each low frequency initiator is associated with a corner location on the vehicle. The vehicle-based unit systematically controls the low frequency initiators to transmit low frequency initiation signals. The tire-based units, in response to receiving a low frequency initiation signal from an adjacent low frequency initiator, transmit tire condition signals. The vehicle-based unit receives the tire condition signals and associates identification numbers received in tire condition signals with the corner location on the vehicle of the low frequency initiator. For example, when a first identification number is received in response to the front left low frequency initiator transmitting an initiation signal, the vehicle-based unit associates the first identification number with the front, left corner location of the vehicle. As a result, the tire condition communication system provides for automatic programming of the corner locations of the tire-based units.